Treatment of textile fibers



United States TREATMENT OF TEXTILE FIBERS No Drawing. Application December 1, 1949, Serial No. 130,603

6 Claims. (Cl. 28-75) The present invention relates to the treatment of textile fibers prior to spinning for the purposes, among others, of improving the inter-fiber friction of such fibers and increasing the tensile strength of the yarn resulting from the further processing and the eventual spinning of the fibers.

It is one object of the present invention to provide an improved method of treating textile fibers prior to spinning to produce fibers having increased inter-fiber friction and other improved properties and which are readily spun into yarns of high tensile strength and at the same time avoid the formation of sticky fibers or the generation of excessive amounts of fly during the manipulation of such fibers prior to and during spinning.

Still further objects and advantages of this invention will appear from the following description and the appended claims.

This invention is carried out, in general, by applying to textile fibers at some stage of their processing prior to spinning, an aqueous dispersion of fine, discrete, unagglomerated particles of a hard, non-plasticized, water-insoluble, polymerized thermoplastic resin which is substantially resistant to plasticization with water and is non-film-forming at temperatures below 150 F. The dispersion is supplied to the fibers in an amount sufiicient to deposit from 0.1 to 3% by weight of the resin and not more than 40% by weight of water, both based on the weight of the fibers. The fibers are then allowed to dry while they are further processed and without heating the fibers.

The dispersion may contain anionic surface active agents since the dispersions employed in this invention are prepared in most instances by the emulsion polymerization of suitable unsaturated organic compounds in the presence of anionic surface active agents. The dispersions should, however, be free of cationic surface active agents which cause the resin to exhaust onto the fibers since the resin first agglomerates and then exhausts on the fibers resulting in the deposition of large, non-uniform particles on the fibers. The dispersions should also be free of multivalent metals which also render the resin substantive, and should also be free of agents which agglomerate or coagulate the resin particles. Anionic surface active agents are preferably used in the dispersion to assist the penetration of the dispersion through the fiber mass.

As examples of textile fibers which are treated in accordance with the methods of the present invention may be mentioned wool fibers, cotton fibers, mixtures of wool and cotton fibers, synthetic staple fibers such as staple fibers prepared from regenerated cellulose, cellulose esters, cellulose ethers, synthetic linear polyamides, polyacrylonitrile, copolymers of vinyl chloride and vinyl acetate and the like or mixtures of such synthetic staple fibers with cotton and/ or wool; or such natural fibers'as linen, flax and the like. The preferred fibers are wool or cotton or mixtures thereof.

The aqueous dispersions employed in accordance with atent O" 2,730,790 Patented Jan. 17, 1956 this invention may be prepared in a variety of ways provided the dispersion is sufficiently stable to permit its application to the fibers without settling or agglomeration of the resin particles therein and providing also that it is substantially free of cationic surface active agents, multivalent metals and resin agglomerating agents. Such dispersions are known in the resin art and are commercially available. A satisfactory method for preparing dispersions or suspensions in the case of resins which cannot be prepared by emulsion polymerization involves dispersing extremely finely divided resin particles in water with the aid of an anionic surface active agent by mixing in a high speed stirrer, a colloid mill or a homogenizer. This result may also be achieved by mixing such ingredients in a ball mill until the resin particles remain suspended.

A preferred method for forming the aqueous dispersions is to polymerize in an aqueous emulsion suitable gaseous or liquid monomeric unsaturated organic compounds which when sufficiently polymerized are hard and waterinsoluble materials and are also non-filrn-forming when dried at room temperature. Polymerization of such monomeric compounds in an aqueous emulsion is generally carried out by first dispersing the monomers in water with an anionic surface active agent to form an aqueous emulsion and then heating the resulting emulsion either in the presence or absence of a polymerization catalyst. The polymerization may also be carried out at room temperature or even lower temperatures in the presence of actinic radiation and/or a polymerization catalyst. Gaseous monomers can be emulsion polymerized in a low pressure autoclave.

As examples of monomeric substances which are use ful in the preparation of the aqueous dispersions by emulsion polymerization techniques may be mentioned styrene; vinyl chloride; nuclear substituted chloro-styrene; acrylonitrile; vinylidene chloride; or combinations of one or more of these monomers with divinylbenzene; mixtures of styrene, vinyl chloride or vinylidene chloride and fumaro-nitrile or acrylonitrile; mixtures of from to 99% by Weight of styrene or chlorostyrene and from 20 to 1% by weight of butadiene or isoprene; mixtures of from 80 to 99% by weight of styrene, chloro-styrene, vinyl chloride or vinylidene chloride and from 20 to 1% by weight of alkyl acrylates containing from 1 to 4 carbon atoms in the alkyl group, alkyl methacrylates containing from 1 to 4 carbon atoms in the alkyl group or mono or dialkyl esters of maleic or fumaric acid containing from 1 to 6 carbon atoms in the alkyl group; mixtures of from to 99% by Weight of vinyl chloride and from 15 to 1% by Weight of vinyl acetate; and mixtures of from 65 to 99% by weight of styrene, chloro-styre'ne, vinyl chloride or vinylidene chloride and from 35 to 1% by weight of methyl acrylate, methyl methacrylate or dimethyl maleate. Improved hardness and resistance to plasticization by water can be obtained by using a crosslinking agent such as divinyl benzene. The above list is not exhaustive since any gaseous or liquid monomeric unsaturated compounds which polymerize in an aqueous emulsion to form aqueous dispersions of fine, discrete, unagglomerated particles of a hard, water-insoluble, nonplasticized thermoplastic resin which is non-film-forming and non-plasticizable by water may also be used.

Aqueous dispersions prepared by the emulsion polymerization of styrene are preferred for use in the methods of this invention because they give excellent results and are cheap and readily available. These dispersions and the dispersions prepared from the monomeric unsaturated compounds described above should be substantially free of monomers, however, since the monomers tend to plasticize the'resin in the dispersion and thus render it sticky or even film-forming. Such monomers can be kept at a minimumby carrying the polymerization to substantial comnle enrfq xamp e. e si the pe ym zat n time or by distilling off the monomers.

Polymers or copolymers produced from any of the combinations of unsaturated compounds mentioned abovernay be polymerized in other ways or coagulated after emulsion polymerization and then ground up into extremely fine particles and dispersed mechanically in the manner hereinbefore described to form suitable aqueous dispersions.

As examples of anionic surface active agents which are usef ul in preparing emulsion polymers of the type described above or which are useful for dispersing finely divided thermoplastic resins suitable for the preparation of the aqueous dispersions may be mentioned water-soluble alkali metal salts of saturated and unsaturated fatty acids containing 10 or more Carbon atoms, water-soluble alkali metal salts of alkylated naphthalene sulfonic acids or of alkylated benzene sulfonic acids, water-soluble alkali metal salts of sulfated or sulfonated fatty alcohols containing 10 or more carbon atoms or the like.

The aqueous dispersions employed in this invention generally have a pH between about 5 and 8 depending upon the materials used in their preparation and the conditions under which they are prepared. However, it is also possible to use dispersions having a higher pH than 8 or a lower pH than 5. For example, wool may be treated without appreciable loss in tensile strength with acidic or mildly alkaline dispersions while cotton and other cellulosic materials do not show any appreciable lossin strength when alkaline orrnildly acidic dispersions are employed. Some synthetic staple fibers, for example, Cellulose acetate or polyarnides may require treatment with neutral or substantially neutral dispersions.

The resin concentration of the aqueous dispersions is generally between 0.5 and 70% by weight and preferably between 10 and 55% by weight. This factor is largely dependent .on the nature of the textile fiber being treated. For example, in the case of cellulosic fibers such as cotton fibers and regenerated cellulose fibers best results are obtained when a minimum of water is added to the fibers with the resins. In such instances when 0.1 to 3% by weight, base on the weight of the fibers, of resin is applied, the amount of water applied is not in excess of 6% by weight .of the weight of the fibers. This means, normally, that the aqueous dispersion should not contain less. than about 33% by weight of resin for the application of 3% by weight of resin on the fibers and not less than 2% by weight resin for the application of 0.1% by weight resin on the .fibers.

Wool fibers and similar animal fibers, on the other hand, can be wetted with larger amounts of water than cotton and regenerated cellulose fibers without interfering with the manipulative characteristics of the fibers. Thus animal fibers which are processed in the woolen system or in the Bradford or French systems can tolerate the addition .of up to about 35% by weight and in some instances .up to by weight of water, based on the weight of fibers. Normally, wool fibers are treated-with from 15 to 20% by weight of water and with from 5 to 10% by weight of oil, both percentages being based on the fiber weight, during the processing of such fibers.

In accordance with the present invention the water normally applied with the wool oil is supplied to the fibers by using the aqueous dispersion of the resin per se or by using such dispersion and additional quantities of water, if such additional quantities of Water are necessary. In those instances when 0.1- to 3% by weight of resin, based on the, weight of the wool fibers, is applied, the amount of water applied is, preferably, in the range of from 5 to 20% by weight based on the weight of the fibers, although larger amounts as high as 40% by weight may be used. This means, normally, that the aqueous dispersion preferably contains not less than about 40% resin for the application .of 3% by weight resin and 5% water on the fibers, or preferably not less than 15% by weight resin for the application of 3% by weight resin and 20% by weight water on the weight of wool fibers. In those instances where it is desired to apply 0.1% by weight resin and 5% by weight water on the fibers, the aqueous dispersion preferably contains not less than 2% by weight resin, or when it is desired to apply 0.1% by weight resin and 20% by weight of water, the aqueous dispersion preferably contains not less than 0.5% by weight resin.

The amount of water which can be applied with the resin to other fibers, for example, synthetic staplefibers such as linear polyamide staple fibers, celluloseester'staple fibers, cellulose ether staple fibers or the like is generally the same as in the case of cotton fibers or is intermediate between the amount applied to cotton fibers and wool fibers.

It is thus seen that the resin is applied to the textile fibers in amounts of 0.1 to 3% by weight, based on the Weight of the fibers, and that the amount of water applied with the resin is up to 40% by weight, basedon the weight of the fibers, depending upon the particular fiber which is being processed. Again, the resin concentration of the aqueous dispersions varies between 0.5 and 60% by weight depending on the amount of resin applied to the fibers and the particular fiber being treated.

The aqueous dispersions hereinbefore defined may-be applied to textile fibers at any stage of their processing prior to spinning. In the case of wool and other animal fibers which are processed according to the wool system it is preferred to apply the aqueous dispersions to the wool fibers just prior to the blending box. Application is generally made by spraying or sprinkling the disper? sion on the fibers until the desired amount of resin and water has been applied. Since oil is normally added to the wool fibers, the oil may be incorporated in the dis; persion and applied therewith or it may be added separately. The aqueous dispersion is preferably applied to wool fibers or other animal fibers, which are being pro.- cessed in the Bradford or French systems, at the gill box where the fibers are formed into a sliver. Here the dispersions are applied, for example, by dripping the dis persion on the fibers or by means of the normal squirrel cage applicator either with oil or by applying the disper-, sion and oil separately.

In the case of fibers which are processed according to the cotton system, the aqueous dispersions are preferably appliedeither in the conveying systems between the open.- ers and the pickers, or at the picker hopper, or at the picker lap, or after-the fibers have been carded but before the web from the card is fully condensed to form the sliver. At the first three of the above-named loca: tions, the dispersions are preferably applied by spraying the dispersions on the fibers until the desired amountof resin and water has been applied. In those instances when the fibers are treated after carding but before the formation of the fully condensed sliver, the dispersions may be applied in various ways. For example, one mode of procedure consists in first forming a partially con.- densed web of the carded fibers as they move from the card, which web is thin and generally rectangular in cross section, and then spraying the dispersion in finely divided form on opposite sides and to the same part of theweb as it moves ina vertical plane.

Another mode of procedure is to apply the, dispersion to the interior portion of the sliver by means ofan applicator device as the web of carded fibers is condensed in a customary trumpet. This applicator device includes a hollow tube which is positioned in the trumpet in such a manner that it is substantially coincident with the center of the trumpet and parallel to the direction of movement of the fibers passing through the trumpet, the o rifice 'of the hollow tube terminating inside the trumpet and closely adjacent to the orifice of the trumpet; and also includes means for supplying a liquid to the hollow tube. The aqueous dispersion is supplied to the hollow tube by gravity flow and the dispersion is wiped from the orifice of the tube, as it drips therefrom, by the fibers as they move past the tube on their way through the orifice of the trumpet. The dispersion is thus deposited in the center portion of the sliver as the sliver is formed in the trumpet. The amount of resin and water deposited is regulated by the rate at which the sliver is formed, the rate of flow of the dispersion through the hollow tube, and the resin concentration of the dispersion. The procedure and apparatus used in this mode of operation are described in greater detail in the patent to Siever, No. 2,115,218.

The textile fibers which have been treated with resin and water in the amounts hereinbefore described, are further processed in the normal manner and without being dried. This is an important advantage in that no extra equipment, outside of the spraying equipment or other application equipment used in applying the dispersions, is required. Also, by dispensing with the drying of the fibers it is possible to process the fibers at lower cost and without the danger of softening the resin which softening often results in the formation of neps or other lumps which interfere with the processing of the fibers and cause an increased number of ends down. By using fine, discrete, unagglomerated particles of a hard, nonplasticized, water-insoluble, polymerized resin which is non-film-forming and hydrophobic, it is possible to obtain improved slip resistance, spin the fibers into yarn at a lower twist multiple or to speed up the rate of production without the formation of appreciable amounts of neps or other lumps of fibers and without appreciably increasing the normal number of ends down.

The yarns produced in accordance with the methods of the present invention contain from 0.1 to 3% by weight of fine, discrete, substantially unagglomerated particles of a hard, non-plasticized, water-insoluble, polymerized thermoplastic resin. The resin particles are distributed throughout the length of the yarn. These yarns are characterized by increased tensile strength at normal twist multiples or by normal tensile strength at lower twist multiples than can normally be used and in the latter case are softer and fuller than yarns prepared without the addition of such resin. They are further characterized in that they are relatively free of neps and by the fact that the fibers therein are not bound together by the resin and are free of resin film.

A further understanding of the present invention will be obtained from the following specific examples which are intended to be illustrative of the invention but not limitative of the scope thereof, parts and percentages being by weight unless otherwise specified.

Example I 1 An aqueous dispersion of polystyrene resin was first prepared as follows: I

Forty parts of monomeric styrene, 0.1 part of KzSzOe as a catalyst, 1.2 parts of the sodium salt of dodecyl benzene sulfonic acid as an emulsifying agent, 0.07 part of sodium dihydrogen phosphate and 0.28 part of disodiurn hydrogen phosphate as buffering agents, and 58.2 parts of water were first agitated to form an emulsion. The emulsion was then heated at a temperature between 90 and 95 C. for 2 hours under a reflux condenser and then cooled rapidly to room temperature. The resulting dispersion contained 40% by weight of fine discrete, unagglomerated particles of hard, water-insoluble and non-plasticized polystyrene resin which was nonfilm-forming when placed on a watch glass and allowed to dry at room temperature. The dispersion also contained about 0.3% by weight of free monomer. The pH of the dispersion was between 7.0 and 7.5 as measured by indicator paper.

The above dispersion was diluted with water until it contained polystyrene solids. This dispersion was then applied to a web of 1%; inch regenerated cellulose (viscose) staple fibers, as the web was being condensed into a sliver, by means of .a hollow tube which was inserted into the central portion of the sliver as it was formed in such a way that the dispersion was taken up by the fibers by a wiping action as the sliver passed by the tube. The type of apparatus and the method of application employed are described in detail in U. S. Patent No. 2,115,218, hereinbefore referred to. The dispersion was supplied to the hollow tube in an amount sufiicient to provide 0.25% polystyrene resin and 2.5% water, both based on the weight of the fibers in the sliver, and throughout the entire length of the sliver.

The resulting sliver was drawn twice and then made into a roving in the normal manner. During the drawing the sliver exhibited a considerably increased resistance to slippage, indicating that the inter-fiber friction had been increased by the resin treatment. To compensate for this increased resistance to slippage the drawing was conducted by opening up the drawing roll settings.

A control roving was prepared from 19% inch regenerated cellulose (viscose) staple fiber in the normal manner and without the resin treatment.

The treated roving and control rovings were then tested for break factor with the following results:

The treated roving gave no difficulty during spinning and enabled the spinning of a yarn having good tensile strength at reduced twist multiple.

Example 11 An aqueous dispersion of polystyrene resin was first prepared as described in Example I and was then diluted with water until it contained 5% polystyrene solids. This dispersion was then mixed with a self-emulsifiable wool oil, the wool oil being added in amounts sufficient to equal the weight of polystyrene in the dispersion. The resulting dispersion was sprayed in the form of finely divided droplets on clothing wool fibers in the blending box in an amount sufiicient to deposit 0.5% of polystyrene particles, 0.5% of the wool oil and 10% of water, all percentages being based on the weight of the fibers. The fibers were then processed into wool yarns according to the wool system of processing and spinning. The fibers were processed without ditficulty, but did exhibit an increased drag or resistance to slippage during the processing operations. The resulting yarn was relatively free of neps or lumps of fibers and the processing machinery showed no evidence of resin accumulation.

Control yarns were prepared from clothing wool in the same manner except that no polystyrene resin was used.

The treated and control yarns were tested for tensile Example III An aqueous dispersion containing 15% by weight of fine, discrete, unagglomerated particles of a hard, non-plasticized, water-insoluble, polyvinyl chloride which is substantially resistant to plasticization with water and nonfilm-forming at temperatures below F., prepared by the emulsion polymerization of vinyl chloride, and about 1.5% of decyl benzene sodiumsulfonate as a dispersing agen'f was sprayed 'in the form of -fir'ie droplets on 1 /3 in'ch Str'itMiddling cotton at the cotton picker hopper. The dispersion was supplied in an amount sufiicient to deposit 0.75% polyvinyl chloride particles and 5.0% water, both percentages based on the Weight of the fibers. The treated fibers Were'made into laps,'and then carded, drawn androved on regular mill equipment. In order to spin the r'ovin'g into yarn it was necessary to reduce'the' normal roving twist by 20%.

The roving was spun into 10s, 20s and 30s yarns which had appreciably more tensile strength than similar yarns prepared from the same cotton fibers but which were nottreated with resin.

The' aqueous dispersions employed in accordance 'with the present invention may be modified by the addition of textile conditioning agents other than the anionic surface active agents or oil's heretofore described. Thus it is possible to add small amounts, i. e., 0.1 to 5% by weight of softening agents, humcctant's, hygroscopic agents, lubricants, non-ionic surface active agents and the like providing, of course, that such agents are not cationic surface agents or agglomerating agents or do not plasticize thethermop'lastic resinparticles.

Various modifications and changes may be made in the dispersions and methods hereinbefore described as will be apparent to those skilled in the art without departing from the spirit and intent of this invention. Accordingly 'it is intended that the present invention be limited only by the scope of the appended claims.

What is claimed is:

1. The method of spinning textile fibers which comprises applying to said fibers at some stage of theirproeess'ing .prior to spinning an aqueous dispersion of "fine,

"discrete, unagglomerated particles of a hard, water-insoluble, non-plasticized polymerized thermoplastic resin in an amount sufiicient to deposit from 0.1 to 3% by weight of said resin and up to 40% by weight of water, based-on the weight of the dryfibers, said dispersion being free of cationic surface active agents, said resin being further characterized in that it is substantially resistant to plasticization by water and isnonfilm-forming at temperatures below 150 F., allowing the fibers to dry at a tem perature below 150 F., and then spinning the resulting fibers to form a'yarn.

2. The method accordingrto claim 1, but further characterized in that the textile fibers are wool fibers.

3. The method of spinning cellulosic textile fibers which comprises applying to said fibers at some stage of their processing prior to spinning an aqueous dispersion of fine; discrete, unagglomerated particles of a hard, water-insoluble, non-,pla .icized polymerized thermoplastic resin in an amount sufiicient to deposit from 0.1 to 3% by weight of said resin and up to 6% by weight of water, based on the weight of the fibers, said dispersion being free of cationic surface active agents, 'saidresin being further characterized in that it is substantia-lly resistant to .plastic izat-ion with water and is non-film-forming at temperatures below 150 F., allow ing the fibers to dry at a temperature below 150 F.

and then spinning the resulting fibers to "form a'yar'rr.

4. The method of spinning textile fibers which comprise's'applyingt'o said fibers at some stage of their processing prior to spinning an aqueous "dispersion of fine, discrete, 'unagglomerated particles of a hard, water-insoluble, non-plasticized polystyrene in an amount sufiicie'nt to de'posit'from 0.1 to 3% by weight ofpolysty're'ne and up to 40% by weight of water, based on' the weight of the fibers, said di persion being free of cationic surface active agent's, allowing the fibers to dry at a temperature below 150 F. and then spinning the resulting fibers to form a yarn. i

5. The method of spinning textile fibers which comprises applying to said fibers at some stage of their processing prior to spinning an aqueous dispersio'h of 'fine, discrete, unag'glor'nerat'ed particles of aha'rd', water-insoluble, n'oh-pl'asticized polyvinylchloride in an amount sufficient to deposit from 0.1 to 3% by weight of said polyvinyl chloride andup to 40% by Weight of water, based on the Weight of the fibers, said dispersion being free o f'cati'onic surface active-agents, allowing the fibers to dry at a temperature below 150 F. and the'n spinning the'resulting fibers'tdfor'm a yarn.

61 Th'e method of spinning textile fibers which cornprises applying tofsaid fibers at some'stage of theirproce'ssing prior to spinningah aqueous dispersion of fine, discrete, nnagglomerat ed particles of a hard, water-insoluble, non-plasticized copolyin'er of a. mixture (if from to 99% styrene and 20' to' 1% of an alkyl maleate containing from '1 to '6 carbon atoms in the alkyl group in an amount sufficient to deposit from 0.1 to 3% by Weight of said copoly'm'er'and up to 40% by weight (if water, based on the weight of the fibers, said dispersion being free of cationic surface active agents, allowing the fibers to dry at a temperature below -F. and then spinningthe resulting fibers to form a'yarn.

References Cited inthe file of this patent UNITED STATES PATENTS 2,054,131 Kollek Sept. 15, 1936 2,115,218 Siever Apr. 26, 1938 2,150,569 Whitehead Mar. 14, 1939 2,244,761 Brandwood June 1 0, 1941 2,319,852 Doolittle May 25, 1943 2,343,091 Smith Feb; 29, 19.44 2,343,095 Smith "-5. Feb. 29, 1944 2,350,032 Hager May 30, 1944 2 ,372,433 Koon Mar. 27, 1945 2,416,988 Foulds et al. Mar. 4, 1947 2,424,743 Davis July 29, .1947 2,443,512 Powers June 15, 1948 2,511,895 Bacon June 20, 1950 2,623,266 Hemrni Dec. 30, -1952 OTHER REFERENCES 

1. THE METHOD OF SPINNING TEXTILE FIBERS WHICH COMPRISES APPLYING TO SAID FIBERS AT SOME STAGE OF THEIR PROCESSING PRIOR TO SPINNING AN AQUEOUS DISPERION OF FINE, DISCRETE, UNAGGLOMERATED PARTICLES OF A HARD, WATER-INSOLUBLE NON-PLASTICIZED POLYMERIZED THERMOPLASTIC RESIN IN AN AMOUNT SUFFICIENT TO DEPOSIT FROM 0.1 TO 3% BY WEIGHT OF SAID RESIN AND UP TO 40% BY WEIGHT OF WATER, BASED ON THE WIEGHT OF THE DRY FIBERS, SAID DISPERSION BEING FREE OF CATIONIC SURFACE ACTIVE AGENTS, SAID RESIN BEING FURTHER CHARACTERIZED IN THAT IT IS SUBSTANTIALLY RESISTANT TO PLASTICIZATION BY WATER AND IS NONFILM-FORMING AT TEMPERATURES BELOW 150* F., ALLOWING THE FIBERS TO DRY AT A TEMPERATURE BELOW 150* F., AND THEN SPINNING THE RESULTING FIBERS TO FORM A YARN. 